JP6398786B2 - Database system, database server, database server program, database client, and database client program - Google Patents

Description

  The present invention relates to a database system, a database server, a database server program, a database client, and a database client program, and can be applied to a system that performs data management based on continuous sequence numbers, for example.

  In general, when managing data with order in a database server (hereinafter also referred to as “DB server”), a sequence number that is a registration order number is assigned to each data when registering the data (record). .

  For example, an application (hereinafter, also referred to as “client APL”) on a database client (hereinafter also referred to as “DB client”) manages the sequence number so that sequential sequence numbers can be acquired. It becomes.

  In the case of this method, when there is one DB client, the order of data by sequence numbers can be ensured on the DB server. However, when there are a plurality of DB clients, each client APL independently manages a sequence number, and therefore, consecutive sequence numbers are assigned to each DB client. However, the data on the DB server may not be a unified sequence number.

  For example, as a conventional method for solving this problem, there is a sequence management function (CREATE SEQUENCE phrase) provided in the ORACLE (registered trademark) database (see Non-Patent Document 1). By using this function, since the sequence number is paid out on the DB server side, the above problem can be solved even when there are a plurality of DB clients.

Oracle, Oracle (R) Database SQL Language Reference 11g Release 2 (11.2) "CREATE SEQUENCE", [Online], INTERNET, [Search February 13, 2015], <URL: http://docs.oracle.com/ cd / E16338_01 / server.112 / b56299 / statements_6015.htm>

  However, in the sequence number allocation of a conventional DB server (for example, an ORACLE database server), it is guaranteed that a unique number will be allocated, but it is guaranteed that consecutive numbers will be allocated depending on conditions. is not.

  In other words, in the conventional DB server, even when only four data registration requests are generated in normal operation, for example, the sequence numbers to be paid out may not be consecutive. Specifically, for example, the sequence numbers issued from the DB server may be discontinuous such as 000001, 000002, 000004, and 000007. This occurs when a DB client that requests acquisition of a sequence number competes in a conventional DB server (for example, when a commit fails due to a conflict or the like).

  Further, in the conventional DB server, even when the registration data is rolled back, the issued number is a missing number.

  Therefore, in the conventional DB server, when data is managed by the sequence number control function as described above, the data of the missing sequence numbers (for example, 000003, 000005, and 000006 in the above example) It is difficult to determine whether it is non-existent data or data that existed but was deleted. In such a case, the conventional DB server requires conditions that must be covered by an application program such as generation of deletion history data and management by a deletion flag.

  In the sequence management function of the conventional ORACLE DB server, the management of the sequence number is effective only on the DB server (= instance activated on the DB server) that issued the CREATE SEQUENCE clause. Therefore, in a system employing a conventional ORACLE DB server, there is a problem that it is difficult to use in a system configuration in which the DB server is made redundant.

  In view of the above problems, a database system, a database server, a database server program, a database client, and a database capable of updating database data using consecutive sequence numbers even when a plurality of database clients exist. A client program is desired.

  The first aspect of the present invention is a database system having a plurality of database clients and a database server connected to the database client. (1) The database server is (1-1) a plurality of data and sequence numbers correspond to each other. A database management means for managing the attached database; and (1-2) a sequence number transmission for returning a latest sequence number managed by the database management means when a request for reading the sequence number of the database is received from the database client. (1-3) When a data update request for the database using a sequence number is received from the database client, the data based on the sequence number is registered or unregistered in the database. (1-4) When the determination unit determines that the registration has been completed, error information indicating a data update failure is sent to the database client that is the transmission source of the data update request. (1-5) The database management means updates the data in the database based on the data update request when it is determined as unregistered by the determination means, and (2-5) Each database client includes (2-1) sequence number requesting means for requesting the database server to read the latest sequence number of the database, and (2-2) the sequence acquired by the sequence number requesting means. Sequence number generating means for generating a new sequence number based on the number; (2-3) above Using the sequence number generated by the sequence number generation means, data update request means for requesting the database server to update the data of the database, and (2-4) error information indicating data update failure is notified from the database server. The sequence number requesting unit re-executes the sequence number read request, the sequence number generating unit regenerates the sequence number based on the sequence number obtained again, and the data update requesting unit regenerates the sequence number. And re-execution means for re-executing the data update request based on the sequence number assigned.

  According to a second aspect of the present invention, in the database server connected to a plurality of database clients, (1) a database management means for managing a database in which a plurality of data and sequence numbers are associated; A sequence number transmitting means for returning the latest sequence number managed by the database management means upon receiving a database sequence number read request; and (3) a data update request for the database using the sequence number from the database client. And (4) a case where it is determined that the data based on the sequence number is registered or not registered in the database, and In the above data update request An error information transmitting unit that transmits error information indicating data update failure to the database client of the transmission source; and (5) the database management unit, when the determination unit determines that the data update request is not registered, Based on the above, the database data is updated.

  A database server program according to a third aspect of the present invention provides: (1) database management means for managing a database in which a plurality of data and sequence numbers are associated with each other; a computer installed in a database server connected to a plurality of database clients; (2) sequence number transmission means for returning the latest sequence number managed by the database management means upon receiving a request for reading the sequence number of the database from the database client; and (3) sequence number from the database client. Receiving a data update request for the database using, and a determination means for performing processing for determining whether the data based on the sequence number is registered or unregistered in the database; and (4) the determination To the means When the data registration request is determined to be registered, the database client that is the transmission source of the data update request functions as an error information transmission unit that transmits error information indicating a data update failure. (5) When it is determined that the data is not registered by the determining means, the database is updated based on the data update request.

  According to a fourth aspect of the present invention, in the database client connected to the database server, (1) sequence number requesting means for requesting the database server to read out the latest sequence number of the database included in the database server; Sequence number generating means for generating a new sequence number based on the sequence number acquired by the sequence number requesting means; and (3) using the sequence number generated by the sequence number generating means to store the data in the database on the database server. A data update request means for requesting update; and (4) when the error information indicating data update failure is notified from the database server, the sequence number request means re-executes a sequence number read request, and the sequence number In the generation means Based on the time acquired sequence numbers to regenerate the sequence number, and having a re-executing means for re-execute the data update request based on re-generated sequence number to the data update request means.

  According to a fifth aspect of the present invention, there is provided a database client program comprising: (1) a sequence for making a request for reading a latest sequence number of a database included in the database server, to the database server connected to the database server; A number requesting means, (2) a sequence number generating means for generating a new sequence number based on the sequence number acquired by the sequence number requesting means, and (3) a sequence number generated by the sequence number generating means. A data update request means for requesting the database server to update the data of the database; and (4) when error information indicating a data update failure is notified from the database server, a sequence number is sent to the sequence number request means. Re-execute the read request, cause the sequence number generation means to regenerate the sequence number based on the sequence number acquired again, and re-execute the data update request based on the sequence number regenerated to the data update request means It is characterized by functioning as a re-execution means.

  According to the present invention, even when there are a plurality of database clients and the like, database data can be updated using consecutive sequence numbers.

It is the block diagram shown about the whole structure of the database system (DB system) which concerns on 1st Embodiment. It is the block diagram shown about the functional structure of the database client which concerns on 1st Embodiment. It is explanatory drawing shown about the structural example of the table | surface (data) which comprises the database which concerns on 1st Embodiment. It is the flowchart shown about operation | movement of the database client which concerns on 1st Embodiment. It is the sequence diagram shown about operation | movement of the database system which concerns on 1st Embodiment. It is explanatory drawing shown about the transition of the table | surface (data) which comprises the database which concerns on 1st Embodiment. It is the block diagram shown about the whole structure of the database system (DB system) which concerns on 2nd Embodiment. It is explanatory drawing shown about the structural example of the sequence number management table | surface which comprises the database which concerns on 2nd Embodiment. It is explanatory drawing shown about the structural example of the table | surface (data) which comprises the database which concerns on 2nd Embodiment. It is the flowchart shown about operation | movement of the database client which concerns on 2nd Embodiment. It is explanatory drawing shown about the example of the SQL sentence transmitted to the database server from the database client which concerns on 2nd Embodiment. It is the sequence diagram (the 1) shown about operation | movement of the database system which concerns on 2nd Embodiment. It is the sequence diagram (the 2) shown about operation | movement of the database system which concerns on 2nd Embodiment. It is explanatory drawing (the 1) shown about the transition of the sequence number management table | surface which comprises the database which concerns on 2nd Embodiment. It is explanatory drawing (the 1) shown about the transition of the table | surface (data) which comprises the database which concerns on 2nd Embodiment. It is the sequence diagram (the 3) shown about operation | movement of the database system which concerns on 2nd Embodiment. It is explanatory drawing (the 2) shown about the transition of the sequence number management table | surface which comprises the database which concerns on 2nd Embodiment. It is explanatory drawing (the 2) shown about the transition of the table | surface (data) which comprises the database which concerns on 2nd Embodiment.

(A) First Embodiment Hereinafter, a first embodiment of a database system, a database server, a database server program, a database client, and a database client program according to the present invention will be described in detail with reference to the drawings.

(A-1) Configuration of the First Embodiment FIG. 1 is a block diagram showing the overall configuration of the DB system 1 of this embodiment.

  The DB system 1 includes a DB server 10 and two DB clients 20 (20-1 and 20-2). Note that the number of DB servers 10 and DB clients 20 arranged in the DB system 1 is not limited. In the DB system 1, each device is connected to the network N and can communicate with each other.

  The DB server 10 can be constructed, for example, by installing a program including a database server program in a computer having a CPU, a memory, and the like. Similarly, each DB client 20 can be constructed by installing a program including a database client program in a computer.

  The DB server 10 provides a DB file system 12 for storing database data, and a server process 11 that provides each DB client 20 with a service using the database stored in the DB file system 12 (executes transaction processing). And have. The server process 11 can be constructed using database middleware such as an RDBMS (Relational Database Management System).

  In this embodiment, description will be made on the assumption that the table A is stored in the DB file system 12. In this embodiment, the server process 11 updates the data (record) in Table A in response to a request from the DB client 20 (client APL 21).

  FIG. 3 is an explanatory diagram showing a configuration example of Table A.

  In FIG. 3, one data (record) is illustrated in one line. In this embodiment, the DB server 10 is described as processing the table A in the table format, but the specific database structure processed by the DB server 10 is not limited. As shown in FIG. 3, each data in Table A includes a plurality of item columns including a sequence number column related to the update of the data.

  Next, processing of Table A in the DB server 10 (server process 11) will be described.

  First, in the DB server 10 (server process 11), in the definition of a table (for example, table A) including a sequence number column (hereinafter also referred to as “sequence number column”), “the sequence number column is made unique. "There is a need. If the above conditions are given to Table A, for example, when data is registered with the same sequence number from two DB clients 20-1 and 20-2, a subsequent request will be made. Makes it possible for the server process 11 to detect a double registration error of the sequence number. At this time, the server process 11 can notify the DB client 20 related to the subsequent request of a double registration error.

  The uniqueness of the definition of a table having a sequence number on the DB server 10 means that, for example, when the RDBMS is an ORACLE database, a “unique key constraint” that is a unique constraint is assigned to the sequence number column. To do. However, in this case, it is desirable to use the sequence number column as a primary key because there should be no data in which the sequence number column is not set on the DB server 10. The primary key is a column (key) that has a uniqueness constraint and a column NULL setting that is not allowed (NOT NULL constraint). Note that even when a unique key constraint and a “NOT NULL constraint” are simultaneously given to the sequence number column, it also has the same meaning as the primary key. Therefore, in the DB server 10, instead of setting the primary key in the sequence number column, the unique key constraint and the “NOT NULL constraint” may be set at the same time.

  As described above, the DB server 10 uses the constraint function of the ORACLE database for the sequence number column in Table A to give “primary key constraint assignment” or “unique key constraint and NOT NULL constraint. It is assumed that “constraint assignment” is performed. In this embodiment, the table A is described as an example, but the same restriction may be applied to a table (database) including other sequence number columns.

  Next, the internal configuration of each DB client 20 will be described with reference to FIG.

  The DB client 20 includes a client APL 21 that performs processing (application processing) with access to the database of the DB server 10 and a database access library 22 that provides the DB client 20 (interface) for accessing the DB server 10. And have.

  As the database access library 22, for example, a client library of an ORACLE database can be applied. With the database access library 22, the client APL 21 can issue an SQL to an arbitrary table (database) on the DB server 10, and can register, update, delete, refer to, etc. data in the table.

  The client APL 21 as a database client program includes a sequence number acquisition unit 211, a sequence number generation unit 212, a data update unit 213, and an error analysis unit 214.

  The sequence number acquisition unit 211 performs processing for requesting and acquiring the latest sequence number from the DB server 10. The sequence number acquisition unit 211 obtains the latest sequence number (the maximum value if the sequence number is in ascending order) from the table to be updated on the DB server 10 (for example, a table including a sequence number column such as Table A). get.

  The sequence number generation unit 212 performs processing for generating a new sequence number (sequence number used for the next data processing request) based on the sequence number acquired by the sequence number acquisition unit 211. For example, in the case of an ascending sequence number, if the acquired sequence number is “1”, the sequence number generation unit 212 generates “2” obtained by incrementing (+1) the acquired sequence number as a new sequence number.

  The data update unit 213 uses the sequence number generated by the sequence number generation unit 212 to make a data update request to the DB server 10 (in this embodiment, a record processing request for Table A).

  The error analysis unit 214 performs processing for analyzing a result when the data update unit 213 accesses the DB server 10. When an error is notified from the DB server 10 in response to the data update request requested by the data update unit 213, the error analysis unit 214 analyzes the content of the error and performs processing according to the analysis result. The client APL 21 is controlled. For example, when receiving a double registration error of the sequence number from the DB server 10, the error analysis unit 214 performs retry processing (re-acquisition of the sequence number, re-generation of the sequence number, and re-request of data update). decide.

  In the client APL 21 of the DB client 20, when a sequence number double registration error is notified at the time of data update to the table A (a table having a sequence number column), the sequence number acquisition unit 211 and the sequence number generation unit 212 again Sequence number acquisition / generation is performed. Then, the data update unit 213 retries data update to the table A using the sequence number acquired and generated again.

  As described above, the client APL 21 of the DB client 20 has a retry function for acquiring and generating a sequence number again and registering data when a double registration error occurs in the error analysis unit 214 when updating data to Table A. doing. As a result, the DB client 20 can process the double registration error of the sequence number within the program (in the client APL 21).

(A-2) Operation of the First Embodiment Next, the operation of the DB system 1 of the first embodiment having the above configuration will be described.

  First, the operation of the client APL 21 in the DB client 20 will be described using the flowchart of FIG.

  FIG. 4 shows an operation until data update (new data registration) for the table A occurs in the client APL 21 and the data update is completed.

  In the client APL 21, when data update to the table A occurs, the sequence number acquisition unit 211 first requests the DB server 10 (server process 11) to read the sequence number (latest sequence number) related to the table A. (S101).

  The sequence number acquisition unit 211 can request a sequence number (latest sequence number) related to Table A using, for example, an SQL statement with an image of “SELECT MAX (sequence number) FROM table A;”. The above-mentioned SQL statement has a content indicating that the maximum value of the sequence number is acquired from the record in Table A.

  Next, the sequence number generation unit 212 generates a new sequence number (a sequence number obtained by adding “1” to the acquired sequence number) using the acquired sequence number. Then, using the generated sequence number, the data update unit 213 requests the DB server 10 (server process 11) to update the data in Table A (new data registration) (S102). When the number of records in Table A is 0 (when the sequence number acquisition unit 211 cannot acquire the sequence number), the sequence number generation unit 212 may generate the sequence number “000001” as an initial value. .

  Thereafter, the client APL 21 receives a processing result notification (for example, error or normal termination) from the DB server 10 (server process 11), and determines processing according to the notification content (S103). At this time, when the double registration of the sequence number is notified, the client APL 21 operates from the above-described step S101 to perform a data update retry process (retry process based on the determination of the error analysis unit 214). If notified, the operation starts from step S104 described later.

  When the data update normal completion is received from the DB server 10 (server process 11), the data update unit 213 of the client APL 21 sends the sequence number used for the latest data update to the DB server 10 (server process 11). A data commit request is made using (the latest sequence number generated by the sequence number generation unit 212) (S104), and the process ends.

  Next, the operation when the two DB clients 20-1 and 20-2 request the DB server 10 to update the data in Table A (new record registration) at the same timing will be described with reference to the sequence diagram of FIG. I will explain. FIG. 6 is an explanatory diagram showing transitions in Table A when each device of the DB system 1 operates according to the sequence diagram of FIG. In the sequence diagram of FIG. 5, the initial state of Table A is assumed to be the state of FIG. As shown in FIG. 6A, in the table A, only data of the sequence number “000001” (item 1: “aaa”,...) Is registered in the initial state.

  In the sequence diagram of FIG. 5, for the sake of simplicity, illustration of a commit request sequence corresponding to a data registration request by the DB client 20 is omitted, but all commits after the registration request by the DB client 20 are all performed. Illustrated as successful.

  In this example, the two DB clients 20-1 and 20-2 update the data for registering data in the table A of the DB server 10 at the same timing, and the sequence number read request reaches the DB server 10 at the same time. (S201, S202).

  In this case, the server process 11 of the DB server 10 reads the latest sequence number “000001” from the table A and responds to the requests from the DB clients 20-1 and 20-2 (S 203, S 204, S 205). ).

  Since the DB clients 20-1 and 20-2 each acquire “000001” as the latest sequence number, “000002” is generated as a new sequence number (S206 and S207).

  Next, it is assumed that the DB client 20-2 first transmits a request for registering new data in the table A (data update request) to the DB server 10 (S208). At this time, it is assumed that the data requested by the DB client 20-2 has the sequence number “00002” and the data content “item 1: ccc,...”. Then, in response to the registration request from the DB client 20-2, the DB server 10 registers data (item 1: ccc,...) With the sequence number “00002” in Table A (S209), and the DB client 20-2. A data registration OK is returned (S212). At this point, the contents of Table A are in the state shown in FIG.

  In response to the data registration OK response from the DB server 10, the DB client 20-2 ends the current data registration process (S215).

  On the other hand, it is assumed that a request (data update request) for registering new data in the table A is transmitted from the DB client 20-1 to the DB server 10 at a timing after the above-described step S208 (S210). At this time, it is assumed that the data requested by the DB client 20-1 has a sequence number “00002” and the data content is “item 1: bbb,...”. The DB server 10 receives the registration request of the DB client 20-2, but detects the double registration error of the sequence number because the data with the sequence number “00002” is already registered in Table A ( (S211), data registration NG (NG caused by double registration error of sequence number) is returned to the DB client 20-2 (S213).

  The DB client 20-1 decides to retry data registration in response to data registration NG from the DB server 10 (NG due to double registration error of sequence number) (S214).

  When the data registration retry is started, first, the DB client 20-1 transmits a sequence number read request to the DB server 10 (S216).

  Then, in response to the sequence number read request from the DB client 20-1, the DB server 10 reads the latest sequence number “000002” in Table A (S217) and returns it to the DB client 20-1 (S218). ).

  Next, the DB client 20-1 generates a new sequence number “000003” based on the acquired latest sequence number “000002” (S219).

  Next, the DB client 20-1 transmits a request (data update request) to register new data in Table A to the DB server 10 using the generated sequence number “000003” (S220). At this time, the data requested by the DB client 20-1 has a sequence number “00003” and the other contents are “item 1: bbb,...” (The same contents as the first data registration request made). And

  Then, in response to the registration request from the DB client 20-1, the DB server 10 registers data (item 1: bbb,...) Having the sequence number “00003” in Table A (S221), and the DB client 20-2. Data registration OK is returned (S222). At this time, the contents of Table A are in the state shown in FIG.

  Next, the DB client 20-1 receives the data registration OK response from the DB server 10, and ends the current data registration process (S223).

(A-3) Effects of First Embodiment According to the first embodiment, the following effects can be achieved.

  In the DB server 10 of the first embodiment, in response to a data registration request from a plurality of DB clients 20, a sequence number is assigned for each registered data, and data registration using the assigned sequence number is accepted. Further, the DB server 10 compares the sequence number of the already registered data with the sequence number of the data for which the registration request has been newly received, and transmits an error to the DB client 20 in the case of double registration. To do. When the DB client 20 accepts the error, the DB client 20 issues a sequence number to the DB server 10 and retries a data registration request. With such a sequence operation, the DB server 10 can maintain continuity of sequence numbers in the database even when there is a request for data registration from a plurality of DB clients 20 at the same time. Therefore, for example, in the DB server 10 of the first embodiment, when there is data with discontinuous sequence numbers, it can be determined that the data related to the missing sequence numbers has been deleted.

(B) Second Embodiment Next, a second embodiment of the database system, database server, database server program, database client, and database client program according to the present invention will be described in detail with reference to the drawings.

(B-1) Configuration of the Second Embodiment FIG. 7 is a block diagram showing the overall configuration of the DB system 1A of the second embodiment. The same or corresponding parts have the same reference numerals or corresponding parts. The code | symbol is attached | subjected. The internal configuration of the DB clients 20-1 and 20-2 of the second embodiment can be shown using FIG.

  Hereinafter, the difference between the second embodiment and the first embodiment will be described.

  In the first embodiment, the method of making the sequence number completely unique (unique) has been described. That is, in the first embodiment, a method for infinitely increasing the acquisition of a sequence number has been described, but in the second embodiment, a sequence number is provided with an upper limit and reused cyclically (hereinafter referred to as “circulation method”). Is also applied).

  In the DB server 10, when the sequence number is used in a circulating manner, the condition “make the sequence number column unique” described in the first embodiment cannot be applied as it is. For example, when the sequence number circulation condition (the range of the payout sequence number) is 000001 to 000100, the sequence number generated when the 101st data is registered is 000001. In this case, in the first embodiment, a sequence number double registration error occurs.

  Therefore, the DB server 10 of the second embodiment creates and holds a management table C for managing sequence numbers in the DB file system 12 in order to avoid the double registration error described above. The DB server 10 according to the second embodiment has a table B that manages data (records) with sequence numbers managed by the sequence number management table C.

  FIG. 8 shows a configuration example of the sequence number management table C. FIG. 9 shows a configuration example of Table B.

  Each data (record) in Table B includes a sequence number managed in the sequence number management table C and the contents of other items (item 1,...). In the sequence number management table C, the sequence number of the most recently registered data in the table B and the registration date and time are managed.

  In Table B shown in FIG. 9, 101 pieces of data are registered. In Table B shown in FIG. 9, the sequence number is rotated once from 000001 to 000100, and is circulated and reused in 000001. That is, in Table B shown in FIG. 9, two pieces of data with sequence number 000001 are registered. In Table B shown in FIG. 9, the latest sequence number is 000001. FIG. 8 shows the contents of the sequence number management table C when the table B is in the state shown in FIG. In the sequence number management table C shown in FIG. 8, 000001 is registered as the latest sequence number in Table B.

  As described above, in the second embodiment, since the sequence number management table C is provided separately from the table B, in the table B (a table for registering data including the cyclic sequence number), the “sequence number column” The condition of “being unique” can be excluded.

  In the second embodiment, since the configuration is divided into the table B and the sequence number management table C, the operation when the DB client 20 (client APL 21) updates the data in the table B is also the first. There are parts different from the embodiment.

  The sequence number acquisition unit 211 of the second embodiment performs a process of reading the latest sequence number from the sequence number management table C.

  A sequence number read request for the sequence number management table C (a table adopting the sequence number circulation method) can be made with an SQL statement of an image as shown in FIG. The SQL statement in FIG. 11A is the data (record) in the sequence number management table, and the content for acquiring the sequence number from the most recently registered data (the most recently registered data). Yes. Thereby, the sequence number acquisition unit 211 can acquire the value of the current latest sequence number.

  The sequence number generation unit 212 of the second embodiment cyclically generates a new sequence number based on the sequence number acquired by the sequence number acquisition unit 211. That is, the sequence number generation unit 212 corresponds to a function of initializing the sequence number to the minimum value when the maximum value in the circulation condition of the sequence number (hereinafter also referred to as “circulation maximum value”) is acquired. For example, when the sequence number circulation condition is 000001 to 000100 and the sequence number acquired from the sequence number management table C is 000100, the sequence number generation unit 212 sets the next used sequence number to 000001. .

  Then, the data update unit 213 of the second embodiment makes a data update request to the table B after the sequence number generated by the sequence number generator 212 is successfully registered in the sequence number management table C. Become. At this time, the data update unit 213 of the second embodiment makes a data update request using the sequence number that has been successfully registered in the sequence number management table C.

  Further, the data (record) in the sequence number management table C needs to have a smaller number of data than the circulation condition. In this embodiment, description will be made assuming that the client APL 21 corresponds to the process of deleting data past the latest sequence number (data other than the latest sequence number) in the sequence number management table C.

  In the example of the second embodiment, when the data update unit 213 registers a new sequence number (new data) in the sequence number management table C, the image SQL statement as shown in FIG. Then, a request for “a process of deleting all data (records) having a sequence number earlier than the most recently registered sequence number” may be made. In this way, by deleting past data from the latest sequence number from the sequence number management table C, only one latest data remains in the sequence number management table C. Note that the entity that requests deletion of data past the latest sequence number in the sequence number management table C is not limited to the DB client 20 and may be performed on the DB server 10 side. In addition, the timing for deleting past data from the latest sequence number in the sequence number management table C is not limited to registering a new sequence number, but limited to the timing for registering a sequence number of a predetermined number. Also good.

(B-2) Operation of the Second Embodiment Next, the operation of the DB system 1A of the second embodiment having the above configuration will be described.

  First, the operation of the client APL 21 in the DB client 20 of the second embodiment will be described using the flowchart of FIG.

  FIG. 10 shows an operation from the occurrence of data update (new data registration) to the table B in the client APL 21 until the data update is completed.

  When data update to the table B occurs in the client APL 21, first, the sequence number acquisition unit 211 sends the sequence number (latest sequence number) related to the sequence number management table C to the DB server 10 (server process 11). A request for reading is obtained (S301).

  Next, the sequence number generation unit 212 cyclically generates a new sequence number (a sequence number obtained by adding “1” to the acquired sequence number) using the acquired sequence number. Then, the data update unit 213 requests the DB server 10 (server process 11) to update the data in the sequence number management table C (new data registration) using the generated sequence number (S302). When the number of data in the sequence number management table C is 0 (when the sequence number acquisition unit 211 cannot acquire a sequence number), the sequence number generation unit 212 generates the sequence number “000001” as an initial value. May be.

  Thereafter, the client APL 21 receives a processing result notification (for example, an error or normal termination) from the DB server 10 (server process 11), and determines processing according to the notification content (S303). At this time, when the double registration of the sequence number is notified, the client APL 21 operates from the above-described step S301 to shift to the data update retry process (retry process based on the determination of the error analysis unit 214), and ends normally. Is notified, the operation starts from step S304 to be described later.

  When the data update normal completion is received from the DB server 10 (server process 11), the data update unit 213 of the client APL 21 sends the sequence number used for the latest data update to the DB server 10 (server process 11). A request for data commit of the sequence number management table C is performed using (the latest sequence number generated by the sequence number generation unit 212) (S304).

  Next, the data update unit 213 of the client APL 21 requests the DB server 10 (server process 11) to delete past data from the sequence number management table C from the latest sequence number (past past the latest sequence number). Request processing for deleting data) (S305).

  Next, the data update unit 213 of the client APL 21 requests the DB server 10 (server process 11) to commit to delete data in the sequence number management table C (S306).

  Next, the data update unit 213 requests data update processing (data registration processing) for Table B using the sequence number registered in the latest sequence number management table C (S307).

  Next, the data update unit 213 requests the DB server 10 (server process 11) to commit data commit of Table B using the sequence number used in the latest data update (S308), and ends the processing. To do.

  Next, with respect to the operation when the two DB clients 20-1 and 20-2 request the DB server 10 to update the sequence number management table C (read the sequence number) at the same timing, FIG. This will be described with reference to the sequence diagram of FIG.

  FIG. 14 is an explanatory diagram showing transition of the sequence number management table C when each device of the DB system 1A operates according to the sequence diagram of FIG. FIG. 15 is an explanatory diagram showing transitions in Table B when each device of the DB system 1A operates according to the sequence diagrams of FIGS.

  In the sequence diagrams of FIGS. 12 and 13, the initial state of the sequence number management table C is assumed to be the state of FIG. As shown in FIG. 14A, in the sequence number management table C, only data of sequence number “000001” (registration date / time: 2013/12/1 13:11:01) is registered in the initial state.

  Further, in the sequence diagrams of FIGS. 12 and 13, the initial state of Table B is assumed to be the state of FIG. As shown in FIG. 15A, in the initial state of Table B, only the data of the sequence number “000001” (item 1: “aaa”,...) Is registered.

  In the sequence diagrams of FIGS. 12 and 13, for the sake of simplicity, illustration of the commit request sequence corresponding to the data registration request by the DB client 20 is omitted. All commits are shown as successful.

  First, it is assumed that read requests for sequence numbers in the sequence number management table C have arrived at the DB server 10 at the same timing from the two DB clients 20-1 and 20-2 (S401, S402).

  In this case, the server process 11 of the DB server 10 reads the latest sequence number “000001” from the sequence number management table C and responds to the requests from the DB clients 20-1 and 20-2 (S403, S404, S405).

  Since the DB clients 20-1 and 20-2 each acquire “000001” as the latest sequence number, “000002” is generated as the new sequence number (S406 and S407).

  Next, the DB client 20-2 first transmitted a request (data update request) to register new data (data with a sequence number “00002”) to the sequence number management table C to the DB server 10. (S408).

  Then, in response to the registration request from the DB client 20-2, the DB server 10 registers the data with the sequence number “00002” in the sequence number management table C (S409), and registers the data registration OK in the DB client 20-2. A response is made (S412). At this time, the contents of the sequence number management table C are in the state shown in FIG.

  Upon receiving a data registration OK response from the DB server 10, the DB client 20-2 requests the DB server 10 to delete past data from the latest sequence number from the sequence number management table C ( S415).

  When receiving the data deletion request for the sequence number management table C from the DB client 20-2, the DB server 10 executes the data deletion for the sequence number management table C in accordance with the request (SQL sentence) (S416). At this time, in the sequence number management table C, the data of the sequence number 000001 that is past (the registration date and time is past) from the latest sequence number of 000002 is deleted. At this time, the contents of the sequence number management table C are in the state shown in FIG.

  Next, the DB client 20-2 requests the DB server 10 to register data in the table B using the sequence number 000002 registered in the sequence number management table C (S421, S422).

  Upon accepting data registration from the DB client 20-2 to Table B, the DB server 10 performs data registration of sequence number 000002 in Table B based on the request (S423), and data registration in the DB client 20-2. OK is returned (S424). At this time, the contents of Table B are as shown in FIG.

  When the data registration OK is received, the DB client 20-2 ends the current data registration process (S425).

  On the other hand, at a timing after step S408 described above, a request (data) for registering new data (data with a sequence number “00002”) from the DB client 20-1 to the DB server 10 in the sequence number management table C. It is assumed that an update request is transmitted (S410). Then, the DB server 10 receives the registration request of the DB client 20-2, but since the data with the sequence number “00002” has already been registered in the sequence number management table C, the double registration error of the sequence number has occurred. Detected (S411), and returns a data registration NG (NG caused by double registration error of sequence number) to the DB client 20-2 (S413).

  In response to the data registration NG from the DB server 10 (NG due to a sequence number double registration error), the DB client 20-1 determines to retry data registration (S414).

  When starting the data registration retry, the DB client 20-1 first transmits a sequence number read request to the DB server 10 (S417).

  Then, in response to a sequence number read request from the DB client 20-1, the DB server 10 reads the latest sequence number “000002” in the sequence number management table C (S418), and returns a response to the DB client 20-1. (S419).

  Next, the DB client 20-1 generates a new sequence number “000003” based on the acquired latest sequence number “000002” (S420).

  Next, the DB client 20-1 transmits a request (data update request) to register new data (data with a sequence number “00003”) in the sequence number management table C to the DB server 10 (S426). .

  Then, in response to the registration request from the DB client 20-1, the DB server 10 registers the data with the sequence number “00003” in the sequence number management table C (S427), and registers the data registration OK in the DB client 20-1. A response is made (S428). At this time, the contents of the sequence number management table C are in the state shown in FIG.

  Upon receiving a data registration OK response from the DB server 10, the DB client 20-1 requests the DB server 10 to delete past data from the latest sequence number from the sequence number management table C ( S429).

  When receiving a data deletion request for the sequence number management table C from the DB client 20-2, the DB server 10 executes data deletion of the sequence number management table C in accordance with the request (SQL statement) (S430). At this time, in the sequence number management table C, the data of the sequence number 000002 in the past (registration date and time) is deleted from 000003 which is the latest sequence number. At this time, the contents of the sequence number management table C are in the state shown in FIG.

  Next, the DB client 20-1 requests the DB server 10 to register data in the table B using the sequence number 000003 registered in the sequence number management table C (S431, S432).

  Upon receiving data registration from the DB client 20-2 to Table B, the DB server 10 performs data registration of sequence number 000003 in Table B based on the request (S433), and data registration to the DB client 20-1. OK is returned (S434). At this time, the contents of Table B are as shown in FIG.

  When the data registration OK is received, the DB client 20-2 ends the current data registration process (S435).

  Next, in the DB system 1A of the second embodiment, an operation when the sequence numbers according to the sequence number management tables C and B are circulated will be described with reference to the sequence diagram of FIG.

  FIG. 17 is an explanatory diagram showing transition of the sequence number management table C when each device of the DB system 1A operates according to the sequence diagram of FIG. FIG. 18 is an explanatory diagram showing transitions in Table B when each device of the DB system 1A operates according to the sequence diagram of FIG.

  In the following description, it is assumed that the maximum circulation number of the sequence number according to the sequence number management table C is set to 100 in the DB system 1A.

  In the sequence diagram of FIG. 16, the initial state of the sequence number management table C is assumed to be the state of FIG. As shown in FIG. 17 (a), in the sequence number management table C, only data of the sequence number “000100” (registration date: 2013/12/11 9:00:00) is registered in the initial state.

  Also, in the sequence diagram of FIG. 16, the initial state of Table B is assumed to be the state of FIG. As shown in FIG. 18A, in Table B, it is assumed that 100 pieces of data of sequence numbers 000001 to 000100 are registered in the initial state.

  In the sequence diagram of FIG. 16, for the sake of simplicity, illustration of a commit request sequence corresponding to a data registration request by the DB client 20 is omitted, but all commits after the registration request by the DB client 20 are all performed. Illustrated as successful.

  Assume that a sequence number read request is transmitted from the DB client 20-1 to the DB server 10 in the above-described state (S501).

  In this case, the DB server 10 reads the latest sequence number “000100” from the sequence number management table C and responds in response to a request from the DB client 20-1 (S502, S503).

  Since the DB client 20-1 acquires “000100” which is the maximum circulation value as the latest sequence number, “000001” is generated as a new sequence number (S504).

  Next, the DB client 20-1 transmits a request (data update request) for registering new data (data with a sequence number “00001”) to the sequence number management table C to the DB server 10 (S505). .

  Then, in response to the registration request from the DB client 20-1, the DB server 10 registers the data with the sequence number “00001” in the sequence number management table C (S506), and stores the data registration OK in the DB client 20-1. A response is made (S507). At this time, the contents of the sequence number management table C are in the state shown in FIG.

  Upon receiving a data registration OK response from the DB server 10, the DB client 20-1 requests the DB server 10 to delete past data from the latest sequence number from the sequence number management table C ( S508).

  When receiving a data deletion request for the sequence number management table C from the DB client 20-1, the DB server 10 executes data deletion for the sequence number management table C in accordance with the request (SQL statement) (S509). At this time, in the sequence number management table C, the data of the sequence number 000100 that is past (the registration date is past) from the latest sequence number 000001 is deleted. At this time, the contents of the sequence number management table C are in the state shown in FIG.

  Next, the DB client 20-1 requests the DB server 10 to register data in the table B using the sequence number 000001 registered in the sequence number management table C (S510, S511).

  Upon receiving data registration from the DB client 20-1 to Table B, the DB server 10 performs data registration of sequence number 000001 in Table B based on the request (S512), and data registration in the DB client 20-1. OK is returned (S513). At this time, the contents of Table B are as shown in FIG.

  When the data registration OK is received, the DB client 20-1 ends the current data registration process (S514).

(B-3) Effects of Second Embodiment According to the second embodiment, the following effects can be achieved.

  In the second embodiment, the sequence number continuity in the DB server 10 can be maintained even in the method of circulating the sequence numbers as in the first embodiment. In the second embodiment, the sequence number is circulated and reused, so that it is possible to operate continuously without considering the upper limit of numerical values that can be used as the sequence number.

(C) Other Embodiments The present invention is not limited to the above-described embodiments, and may include modified embodiments as exemplified below.

  (C-1) In the second embodiment, the sequence number and the registration date / time are registered in the sequence number management table C, but the registration date / time may be omitted. However, if the registration date / time is omitted, the number of data in the sequence number management table C must always be kept below the maximum circulation value.

  DESCRIPTION OF SYMBOLS 1 ... DB system, 10 ... DB server, 11 ... Server process, 12 ... DB file system, 20, 20-1, 20-2 ... DB client, 21 ... Client APL, 211 ... Sequence number acquisition part, 212 ... Sequence number Generation unit, 213... Data update unit, 214... Error analysis unit, 22.

Claims (10)

In a database system having a plurality of database clients and a database server connected to the database client,
The database server
Database management means for managing a database in which a plurality of data and sequence numbers are associated;
Upon receiving a read request for the sequence number of the database from the database client, sequence number transmission means for returning the latest sequence number managed by the database management means,
When receiving a data update request for the database using a sequence number from the database client, a determination unit that performs processing for determining whether data based on the sequence number is registered or unregistered in the database When,
An error information transmitting unit that transmits error information indicating a data update failure to the database client that is the transmission source of the data update request when the determination unit determines that the data has been registered;
The database management means performs data update of the database based on the data update request when it is determined as unregistered by the determination means,
Each of the above database clients
Sequence number requesting means for requesting the database server to read out the latest sequence number of the database;
Sequence number generating means for generating a new sequence number based on the sequence number acquired by the sequence number requesting means;
Using the sequence number generated by the sequence number generation means, a data update request means for requesting the database server to update the database data;
When error information indicating data update failure is notified from the database server, the sequence number requesting unit is caused to re-execute a sequence number read request, and the sequence number is generated based on the sequence number acquired again by the sequence number generating unit. A database system comprising: re-execution means for re-generating a number and re-executing the data update request based on the sequence number re-generated by the data update request means.   2. The database system according to claim 1, wherein each data constituting the database includes a sequence number column in which sequence numbers are registered.   3. The database system according to claim 2, wherein in the database, the sequence number column is guaranteed uniqueness.   The database includes a sequence number management table in which data including sequence numbers is registered, and a data table including data including a sequence number column in which sequence numbers assigned in accordance with the sequence number management table are registered. The database system according to claim 1, wherein: The sequence number requesting unit requests the database server to read the latest sequence number of the sequence number management table,
The data update request means makes a data update request for registering the sequence number generated by the sequence number generation means to the sequence number management table to the database server, and further to the database server to the sequence number management table. Request data update of the above data table using the registered sequence number,
The re-execution unit causes the sequence number request unit to re-execute a sequence number read request when the database server is notified of error information indicating a data update failure, and the sequence number generation unit re-acquires the request. 5. The database system according to claim 4, wherein the sequence number is regenerated based on the sequence number, and the renewed sequence number registration request and the data update request are re-executed by the data update request unit.   6. The database system according to claim 5, wherein the sequence number generation means cyclically generates a sequence number. In a database server that connects to multiple database clients,
Database management means for managing a database in which a plurality of data and sequence numbers are associated;
Upon receiving a read request for the sequence number of the database from the database client, sequence number transmission means for returning the latest sequence number managed by the database management means,
When receiving a data update request for the database using a sequence number from the database client, a determination unit that performs processing for determining whether data based on the sequence number is registered or unregistered in the database When,
An error information transmitting unit that transmits error information indicating a data update failure to the database client that is the transmission source of the data update request when the determination unit determines that the data has been registered;
The database server characterized in that the database management means updates data of the database based on the data update request when it is determined that the registration means is not registered. A computer installed in a database server that connects to multiple database clients
Database management means for managing a database in which a plurality of data and sequence numbers are associated;
Upon receiving a read request for the sequence number of the database from the database client, sequence number transmission means for returning the latest sequence number managed by the database management means,
When receiving a data update request for the database using a sequence number from the database client, a determination unit that performs processing for determining whether data based on the sequence number is registered or unregistered in the database When,
When it is determined that the data has been registered by the determination unit, the database client that is the transmission source of the data update request functions as an error information transmission unit that transmits error information of data update failure,
The database server program according to claim 1, wherein the database management unit updates data of the database based on the data update request when it is determined as unregistered by the determination unit. In the database client that connects to the database server,
Sequence number requesting means for requesting the database server to read out the latest sequence number of the database provided in the database server;
Sequence number generating means for generating a new sequence number based on the sequence number acquired by the sequence number requesting means;
Using the sequence number generated by the sequence number generation means, a data update request means for requesting the database server to update the database data;
When error information indicating data update failure is notified from the database server, the sequence number requesting unit is caused to re-execute a sequence number read request, and the sequence number is generated based on the sequence number acquired again by the sequence number generating unit. A database client comprising: a re-execution unit that re-generates a number and re-executes the data update request based on the sequence number re-generated by the data update request unit. The computer installed in the database client that connects to the database server
Sequence number requesting means for requesting the database server to read out the latest sequence number of the database provided in the database server;
Sequence number generating means for generating a new sequence number based on the sequence number acquired by the sequence number requesting means;
Using the sequence number generated by the sequence number generation means, a data update request means for requesting the database server to update the database data;
When error information indicating data update failure is notified from the database server, the sequence number requesting unit is caused to re-execute a sequence number read request, and the sequence number is generated based on the sequence number acquired again by the sequence number generating unit. A database client program, wherein a number is regenerated, and the data update request unit functions as a re-execution unit that re-executes a data update request based on the re-generated sequence number.

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